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the living body were aptly compared to a circle, 

 in describing which we may begin at any point, 

 and set off in any direction we choose ; and there 

 is certainly no point at which we can begin, but 

 it requires a great deal of previous knowledge to 

 render it at all intelligible, and none which can 

 be in any degree exhausted, without involving 

 more or less, the consideration of almost every 

 other function of the body. One leading ground 

 of distinction, however, between the functions 

 is, that while some of them require only excita- 

 bility in general to be called into action, and are 

 carried on without the consciousness of the indi- 

 vidual, and not only independently of the will, 

 but even against the will, others require some 

 new properties superadded to general excitability, 

 such as sensibility and susceptibility of thought, 

 and are not only attended with consciousness, 

 but subject, in a great measure, to the control of 

 the will. The former of these have been called 

 collectively the organic functions, since they are 

 common, under some modification or other, to 

 all forms of organized beings vegetable as well 

 as animal and include all those to which I have 

 already alluded ; the latter have been called ani- 

 mal functions, since they have been presumed to 

 be characteristic of animals, and include sensa- 

 tion, thought, and voluntary motion. 



Such then, is the ordinary general arrange- 

 ment of the functions of animals, founded on 

 presumed differences in their essential conditions, 

 the former class requiring, for their display, only 



